Objective  In order to accurately locate the zone and size of flow energy loss during the operation of a ducted propeller, the flow energy loss characteristics are analyzed from the perspective of energy.

  Method  Steady ducted propeller simulations are investigated under different advance coefficients and rotational speed conditions by solving the Reynolds-Averaged Navier–Stokes equations and entropy production equation, and the optimization of a ducted propeller with boss cap fins is carried out on this basis.

  Results  The value of viscous dissipation entropy production increases with the increase of the advance coefficient, while the value of turbulent dissipation entropy production decreases with the increase of the advance coefficient at the same rotational speed. At the same advance coefficient, the two kinds of entropy production value increase significantly with the increase of rotational speed. The proportion of turbulent dissipation entropy production is larger than that of viscous dissipation entropy production in different operating modes, so the turbulent dissipation is the main reason for the irreversible flow energy loss. The main flow loss zone is behind the trailing edge of the duct and hub, in which the hub vortex zone formed behind the hub is exactly the high concentration zone of the flow energy loss. In addition, the improved ducted propeller with boss cap fins can significantly improve the vortex distribution at the tail of the propeller and reduce the flow energy loss caused by the hub vortex.

  Conclusions  This study reveals the flow loss mechanism of ducted propellers and accurately locates the flow energy loss concentration zone, offering new insights into the energy-saving optimization design and flow energy loss identification analysis of ducted propellers.